by Byron Gin
In this issue:
New to the Neighborhood
Paleontologist William Clyde spends his summers at a geological site in Wyoming, just outside Yellowstone National Park. For the past 10 years, he's been gathering fossils and rock samples in this dry land, where only desert plants can grow. But the Badlands weren't always like this, Clyde says.
At the end of the Paleocene epoch, about 55.5 million years ago, the Earth's climate was warm and wet. Magnolia trees and murky swamps covered what is now Wyoming, and archaic mammals prowled the subtropical rain forest. Pantodonts, similar in appearance to pygmy hippos, shared the canyon jungle with bulky hoofed herbivores called amblypods. Primitive flesh-eating creodonts, ranging in size from small weasels to large bears, walked flat-footed on short, heavy limbs. Condylarths, which resembled prairie dogs, ranged across the swamps.
But there were no modern mammals in North America during the Paleocene. They did not appear until the climate became suddenly warmer between the late Paleocene and the early Eocene epochs. This dramatic climatic event, known as the late Paleocene thermal maximum, lasted 80,000 to 100,000 years --a short time, geologically speaking. The change in climate triggered a migration with long lasting effects on the ecosystem, as modern mammals made their way to North America. "The fossil record shows a sudden appearance of the modern orders of mammals in the Bighorn Basin. They appear so suddenly and look so different from Paleocene mammals that they must have moved into the area," explains Clyde, an assistant professor of geology at UNH.
Where did the mammals come from? Clyde believes that Asian and European migration corridors are good possibilities. At that time, Asia and North America were linked by a land bridge across the Bering Strait, while Europe and North America were linked by a bridge by way of Greenland. The two bridges were off limits to mammals before the thermal maximum, because the climate at those latitudes had been too cold. But as the temperatures warmed, early ancestors of bats, primates, odd-toed ungulates such as horses and rhinoceroses, and even-toed ungulates like sheep and antelope were able to wander in. European and Asian scientists are trying to understand the cause of the sudden warming so they can determine if it could happen again, and what would happen if it did. One theory about the cause of the sudden global warming is that an enormous reservoir of frozen methane gas was somehow released. The gas would have bubbled up through the ocean into the atmosphere, resulting in intense levels of carbon-12.
Whatever the cause, the rise in temperature was dramatic. In Wyoming, the mean annual temperature before the late Paleocene thermal maximum was about 16 to 17 degrees Celsius. During the event, the temperature fluctuated between 20 and 21 degrees Celsius. Today, Wyoming's mean annual temperature ranges from 5 to 10 degrees Celsius. "In general, the late Paleocene thermal maximum represents the warmest period in the last 80 million years of Earth history, so it is very significant," Clyde says.
The only fossil mammals from that time have been found in the rocky formations rising above Wyoming's Bighorn Basin. Over the past century, paleontologists have cataloged more than 500,000 specimens recovered there, including the first fossil evidence of true primates and ancestral relatives of horses, tapirs and elk. With a three-year grant from the National Science Foundation, Clyde hopes to find out how the influx of these animals affected the structure of the mammal community in the region.
--Nancy Eichhorn '92G
Adolescence is hard enough under the best of circumstances. Imagine being a teenager who was adopted from a foreign country and raised in suburban New England. You're different from your Anglo classmates, which didn't matter much while you were very young, but now you feel like you'll never fit in.
Robert Jolley knows how tough those teen years can be for international adoptees. An associate professor and chair of the Department of Social Work at UNH, he is an adoptive father to two children born in Colombia. Now 19 and 22 years old, they have left behind the tumult of adolescence, but Jolley is still involved with teens just like them.
Jolley's research has shown that international adoptees--up to 15,000 annually in the United States--experience more social and emotional problems than do children who are adopted domestically. "Around the age of 10, adopted children have a sense of being separated, of being given away," Jolley says. "It's not a problem until the kids cannot find a place where they feel comfortable."
The emotional toll of racial and cultural alienation can be devastating for young people. Their responses run the gamut from mental anguish and substance abuse to serious criminal behavior. Jolley's work has helped mental health practitioners to understand the long-term needs of international adoptees. "What's new in the last 10 to 15 years is the realization that adoption really is a lifelong process," he says.
Jolley's first study, 12 years ago, assessed the social, academic and behavioral adjustment of more than 500 children, mostly Colombian, who had been placed in families by the Florence Crittenton League, a nonprofit agency in Lowell, Mass. Based on his work, remedial intervention programs have been developed to help the Colombian teenagers come to terms with their heritage and their future.
This year, Jolley is repeating the study with children from Russia and China. He expects to find evidence of learning difficulties or behavioral problems at a younger age because of fetal alcohol syndrome in the Russian children and malnutrition in the Chinese children. His goal is to define and address the needs of these children before the onset of adolescence and help them avoid the emotional difficulties later on.
--Michelle Gregoire '99
Everyone has heard reports about the amount of carbon dioxide released into the atmosphere by human activities and its possible impact on global climate. But tracking the release of carbon dioxide tells only half of the story. It's just as important to know how much of the gas is removed from the atmosphere by forests, cropland and other "carbon sinks."
Scientists have had a hard time estimating just how much carbon is captured by sinks. Two different kinds of measurements have been used, one based on atmospheric carbon dioxide and the other based on inventories of carbon on the ground. But they have produced inconsistent results, and until last summer, scientists couldn't tell which estimates were most reliable.
In a report published in June in the journal Science, 13 scientists from various universities and government agencies combined a number of measurements--both atmosphere- and land-based--to produce a consensus estimate of the total U.S. carbon sink. They concluded that carbon sinks in the 48 coterminous states stored a net 300 million to 580 million tons of carbon each year during the decade of the 1980s.
George Hurtt, research assistant professor in the Institute for the Study of Earth, Oceans and Space at UNH, was one of the report's authors. "Earlier studies indicated that the atmospheric estimates and ground-based estimates were quite far off," he says. "This report helps build consensus about the size and causes of the carbon sink."
During the 1980s, about 7 billion tons of carbon were pumped into the Earth's atmosphere every year in the form of carbon dioxide. Fossil fuel emissions totaled about 5.4 billion tons per year, while logging and burning of forests released approximately 1.6 billion tons per year. About half of the total amount of carbon emitted each year--3.4 billion tons--accumulated in the atmosphere; another 2 billion tons accumulated in the oceans; and about 1.6 billion tons are believed to have gone into land sinks. The Science report indicates that the U.S. carbon sink accounted for somewhere between 19 percent and 36 percent of the estimated global land sink.
Hurtt notes that the sink is large compared to the land area. This is because changes in land use over the past century have had a major impact. The reforestation of agricultural land has particularly facilitated carbon accumulation because trees and other plants absorb large amounts of carbon dioxide as they grow.
Another important factor, Hurtt says, is that the area burned by forest and prairie fires has decreased by 95 percent since the mid-1700s. Consequently, much less of the carbon stored in those ecosystems has been released back into the atmosphere.
Although land sinks reduce the rate at which carbon dioxide accumulates in the atmosphere, the U.S. continues to emit more than it removes. In 1990, for example, the country released 1.337 billion tons of carbon through fossil fuel emissions. That's between 750 million and 1 billion tons more than the amount stored in the U.S. carbon sink in the same period.
"To stabilize the atmospheric carbon dioxide, we have to not only stabilize net emissions, but reduce them," says Hurtt. "To do that, we can reduce fossil fuel emissions, increase the carbon sinks, or both. The sinks absorb 20 to 50 percent of emissions. More could be done in terms of reducing deforestation and replanting trees, but we can't escape the fact that we need to reduce emissions." ~
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